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Stack, Static, and Heap in C++
...t understood very well these three concepts. When do I have to use dynamic allocation (in the heap) and what's its real advantage? What are the problems of static and stack? Could I write an entire application without allocating variables in the heap?
...
How do you write a migration to rename an ActiveRecord model and its table in Rails?
...ble_name
end
end
I had to go and rename the model declaration file manually.
Edit:
In Rails 3.1 & 4, ActiveRecord::Migration::CommandRecorder knows how to reverse rename_table migrations, so you can do this:
class RenameOldTableToNewTable < ActiveRecord::Migration
def change
rena...
Java URL encoding of query string parameters
... are represented by +, not %20, which is legitimately valid. The %20 is usually to be used to represent spaces in URI itself (the part before the URI-query string separator character ?), not in query string (the part after ?).
Also note that there are three encode() methods. One without Charset as s...
ZMQ: 基本原理 - 开源 & Github - 清泛网 - 专注C++内核技术
... 为了强化这个原则，ØMQ严格地分离拓扑的建立（zmq_bind,zmq_connect）和真实消息的传递（zmq_send,zmq_rev)。 前者同底层的传输地址协同工作，比如IP地址，而后者仅仅使用处理器（文件描述符）去定位具体的拓扑： /* Topology esta...
List all tables in postgresql information_schema
What is the best way to list all of the tables within PostgreSQL's information_schema?
8 Answers
...
Pandas every nth row
...simpler solution to the accepted answer that involves directly invoking df.__getitem__.
df = pd.DataFrame('x', index=range(5), columns=list('abc'))
df
a b c
0 x x x
1 x x x
2 x x x
3 x x x
4 x x x
For example, to get every 2 rows, you can do
df[::2]
a b c
0 x x x
...
What is the difference between the OAuth Authorization Code and Implicit workflows? When to use each
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The access_token is what you need to call a protected resource (an API). In the Authorization Code flow there are 2 steps to get it:
User must authenticate and returns a code to the API consumer (called the "Client").
The "client" of the API (usually your web s...
How to explicitly discard an out argument?
...ublic void PrintXCoordinate(Point p)
{
p.GetCoordinates(out int x, out _); // I only care about x
WriteLine($"{x}");
}
Source: https://blogs.msdn.microsoft.com/dotnet/2017/03/09/new-features-in-c-7-0/
share
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Change one value based on another value in pandas
...ere.
Assuming you can load your data directly into pandas with pandas.read_csv then the following code might be helpful for you.
import pandas
df = pandas.read_csv("test.csv")
df.loc[df.ID == 103, 'FirstName'] = "Matt"
df.loc[df.ID == 103, 'LastName'] = "Jones"
As mentioned in the comments, you ...
How do I perform a Perl substitution on a string while keeping the original?
...
I was wondering if something like my $new = $_ for $old =~ s/foo/bar; would work?
– Benoit
Apr 30 '14 at 17:11
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